Information recording medium and apparatus and method for recording and reproducing information

ABSTRACT

The data recording/reproducing apparatus of the present invention efficiently performs a trickplay mode operation such as fast forward reproducing and rewind reproducing and a postrecording operation by using a data recording medium storing a variable-bitrate-compressed video data. Each AV file in the video data includes chapter data and first and second pointer data. Each GOP data in the chapter data includes one independent picture data and a plurality of dependent picture data. The first pointer data includes the location data of the independent picture data, and the second pointer data includes the location data of the first pointer data. Further, each GOP data includes an audio data interleaved with the picture data. The first pointer data includes the location data of the corresponding audio data, and the second pointer data includes the location data of the corresponding first pointer data. A hierarchical location data for retrieving the independent picture data and/or the audio data is formed by the first and second pointers.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a data recording medium, a datarecording/reproducing apparatus and a data recording/reproducing methodfor recording/reproducing variable-bitrate-compressed video data andaudio data synchronized with the video data in each unit of a fixedlength. More particularly, the present invention relates to a datarecording/reproducing apparatus and a data recording/reproducing methodthat rapidly performs a recording/reproducing operation of video data,in particular, a trickplay mode operation such as fast forwardreproducing and rewind reproducing by using the data recording mediumand also performs a postrecording operation to rewrite the audio dataalone.

2. Description of the Related Art

Recently, image coding techniques for variable-bitrate-compression ofvideo data in units of a picture have been studied in order to attainfast transfer of mass digital video data and recording of the massdigital video data in a data recording medium having a limited capacity.The MPEG standard, which is one of the image coding techniques,prescribes a compression method for digital video data by combining an Ipicture that is intra-picture (intra-frame or intra-field) compressioncoded and a P picture or a B picture that is inter-picture (inter-frameor inter-field) compression encoded. Such a data compression techniquerealizes the compression of digital video data from, for example, 150Mbps into 3 Mbps.

In this method, however, the compression ratio of the digital video datadepends upon the contents of the video data and the image correlationswithin the previous and subsequent pictures, and hence, each picture hasa largely different capacity. For example, when the average data rate ofthe compressed video data is 3 Mbps, an image with little motion iscompressed into 1 Mbps, while an image with much motion can becompressed into only 10 Mbps. Further, an I picture, a P picture and a Bpicture forming a series of scenes have respectively differentcapacities: on the average it is regarded that the I picture has acapacity approximately twice as large as that of the P picture andapproximately four times as large as that of the B picture on theaverage. Therefore, when video data that is variable-bitrate-compressedin units of a picture is recorded on continuous areas on a medium suchas an optical disk, where sectors each having a fixed length of, forexample, 2 KB (2048 bytes) are previously formed, the location for eachpicture is largely varied. When such a data recording medium storing thecompressed video data is used to perform a trickplay mode operation(such as the fast forward reproducing and the rewind reproducing) usingthe I picture data alone, it is indispensable to efficiently manage thelocation data on the I picture data which is located on the recordingmedium at unequal intervals.

In the MPEG standard, data is compressed in units of a GOP (group ofpictures) including one I picture and a plurality of P pictures and Bpictures. For example, when an NTSC signal for displaying approximately30 pictures per 1 second is compressed into units of a GOP includingtwelve pictures, video data per 1 second includes 2.5 I picture data.Therefore, when a movie title of 135 minutes-is compressed under thiscondition, the title includes as many as 20,250 I picture data. Forrecording all location data of such a large amount of I picture datausing an address of four byte length in one continuous area of a medium,the size of this area is approximately 80 KB. Considering that thebuffer capacity for an audio decoder forming a target decoder systemdescribed in the MPEG standard is limited within only 4 KB, the 80 KBcapacity of a buffer for storing the location data of all I picture datamakes it significantly difficult to realize a compact system.

Further, when variable-bitrate-compressed video data and audio datasynchronized with the video data are interleaved in units of a sector tobe recorded on a recording medium, the audio data is located on therecording medium at unequal intervals even if the audio data is a fixedlength data obtained by non-compression coding orconstant-bitrate-compression coding. Accordingly, when a rewritable datarecording medium where such video data and the audio data are previouslyrecorded is used to rewrite the audio data alone, i.e., to perform apostrecording operation, it is indispensable to efficiently manage thelocation data of the audio data which is located on the medium atunequal intervals.

For example, when stereo audio data is compressed in accordance with theMPEG standard into the data rate of 224 Kbps, i.e., 28 KB/s, a movietitle of 135 minutes includes 226,800 KB of compressed audio data. Whenthe compressed audio data is interleaved with the video data in units ofa 2 KB sector to be recorded on a data recording medium, the compressedaudio data is dispersedly recorded in 113,400 sectors. For recording alllocation data of such a large amount of audio data using an address offour byte length in one continuous area of a medium, the size of thisarea is approximately 450 KB. Further, when the entire audio data in aGOP is recorded in one continuous area, the number of the audio data isidentical to that of the I picture data. Therefore, for recording alllocation data of these audio data in one continuous area, the Size ofthis area is approximately 80 KB. The 450 KB or 80 KB capacity of abuffer is too large as compared with the limitation of buffer capacityfor an audio decoder as described above, resulting in restricting thedesign of compact systems.

SUMMARY OF THE INVENTION

The data recording medium of this invention is a medium having aplurality of units with a fixed length, and is used for recording AVfiles each including the video data that is compressed in units of apicture on the variable-bitrate condition. Each of the AV files recordedon the data recording medium includes a plurality of chapter dataincluding a plurality of GOP data, a plurality of first pointer dataeach having a plurality of first pointers, and at least one secondpointer data having a plurality of second pointers; each of the GOP dataincludes one independent picture data that is intra-picture compressedand a plurality of dependent picture data that are inter-picturecompressed; each of the first pointers is provided in a one-to-onecorrespondence to each of the independent picture data, and storeslocation data of the corresponding independent picture data; each of thesecond pointers is provided in a one-to-one correspondence to each ofthe first pointer data and stores location data of the correspondingfirst pointer data; and a hierarchical location data for retrieving theindependent picture data is formed by the first pointers and the secondpointers.

In one embodiment of the data recording medium of this invention, eachof the chapter data is arranged adjacent to one of the first pointerdata which includes the first pointers corresponding to the independentpicture data included in that particular chapter data.

In one embodiment of the data recording medium of this invention, thechapter data and the first pointer data are alternately located, andeach of the first pointer data includes the first pointers correspondingto the independent picture data included in the chapter data adjacent tothat particular first pointer data.

In one embodiment of the data recording medium of this invention, thesecond pointer data is located at the top and/or end portions of each ofthe AV files, and the second pointer data includes all of the secondpointers corresponding to the first pointer data included in thecorresponding AV file, thereby storing the location data on all of thefirst pointer data included in the corresponding AV file.

In one embodiment of the data recording medium of this invention, eachof the GOP data further includes audio data.

In one embodiment of the data recording medium of this invention, theaudio data is interleaved with the independent picture data and thedependent picture data of the basis of each unit with the fixed length,and a data type code for discriminating the independent picture data isrecorded in each unit with the fixed length.

In one embodiment of the data recording medium of this invention, apadding data is added to the independent picture data, thereby theindependent picture data to which the padding data is added completingeach unit with the fixed length, and a valid data length fordiscriminating the padding data is recorded in each unit with the fixedlength.

The data reproducing apparatus of this invention uses a data recordingmedium having a plurality of units with a fixed length, in order torecord AV files each including the video data that is compressed inunits of a picture on the variable-bitrate condition. Each of the AVfiles including a plurality of chapter data including a plurality of GOPdata, a plurality of first pointer data each having a plurality of firstpointers, and a plurality of second pointer data each having a pluralityof second pointers; each of the GOP data including one independentpicture data that is intra-picture compressed and a plurality ofdependent picture data that are inter-picture compressed; each of thefirst pointers being provided in a one-to-one correspondence to each ofthe independent picture data and storing location data of thecorresponding independent picture data; each of the second pointersbeing provided in a one-to-one correspondence to each of the firstpointer data and storing location data of the corresponding firstpointer data. The data reproducing apparatus comprises: a pointerreproducing means for reading out the first and the second pointer datafrom the data recording medium; a first pointer data storing circuit fortemporarily storing the read first pointer data; a second pointer datastoring circuit for temporarily storing the read second pointer data; acontrol circuit for retrieving the location data of the first pointerdata based on the second pointer data stored in the second pointer datastoring circuit, and retrieving the location data of the independentpicture data based on the retrieved location data of the first pointerdata and the first pointer data stored in the first pointer data storingcircuit; and a picture reproducing means for reproducing a predeterminedpiece of the independent picture data from the data recording mediumbased on the retrieved location data of the independent picture data.

In one embodiment of the data reproducing apparatus of this invention,the control circuit comprises a circuit for selecting the location dataof the independent picture data to be retrieved in accordance with anexternally determined reproducing speed.

In one embodiment, the data reproducing apparatus of this invention usesthe data recording medium in which each of the GOP data further includesaudio data being interleaved with the independent picture data and thedependent picture data of the basis of each unit with the fixed length,a data type code for discriminating the independent picture data beingrecorded on the basis of each unit with the fixed length, and the datareproducing apparatus further comprises a data type discriminatingcircuit for discriminating the data type code recorded in the unit withthe fixed length.

In one embodiment, the data reproducing apparatus of this invention usesthe data recording medium in which a padding data is added to theindependent picture data so that the independent picture data to whichthe padding data is added completes each unit with the fixed length, avalid data length for discriminating the padding data being recorded onthe basis of each unit with the fixed length, and the data reproducingapparatus further comprises a data length detection circuit fordetecting the valid data length recorded in the unit with the fixedlength.

The data reproducing method of this invention uses a data recordingmedium having a plurality of units with a fixed length, in order toreproduce AV files each including the video data that is compressed inunits of a picture on the variable-bitrate condition, each of the AVfiles including a plurality of chapter data including a plurality of GOPdata, a plurality of first pointer data each having a plurality of firstpointers, and at least one second pointer data each having a pluralityof second pointers; each of the GOP data including one independentpicture data that is intra-picture compressed and a plurality ofdependent picture data that are inter-picture compressed; each of thefirst pointers being provided in a one-to-one correspondence to each ofthe independent picture data and storing location data of thecorresponding independent picture data; each of the second pointersbeing provided in a one-to-one correspondence to each of the firstpointer data and storing location data of the corresponding firstpointer data, thereby selectively reproducing the independent picturedata. The method comprises the steps of: receiving an externallysupplied reproducing condition; reading out the second pointer data fromthe data recording medium; temporarily storing the read second pointerdata; searching the stored second pointer data to retrieve the locationdata of the first pointer data satisfying the reproducing condition;reading out the first pointer data from the data recording medium basedon the retrieved location data of the first pointer data; searching thestored first pointer data to retrieve the location data of theindependent picture data satisfying the reproducing condition; andreproducing the independent picture data from the data recording mediumbased on the retrieved location data of the independent picture data.

In one embodiment of the data reproducing method of this invention, thereproducing condition includes a reproducing speed, and in the step ofretrieving the location data of the independent picture data, thelocation data of the independent picture data to be retrieved isselected in accordance with the reproducing speed, thereby adjusting theinterval between the independent picture data that is to be reproduced.

In one embodiment, the data reproducing method uses data recordingmedium in which each of the GOP data further includes an audio databeing interleaved with the independent picture data and the dependentpicture data on the basis of each unit with the fixed length, a datatype code for discriminating the independent picture data being recordedon the basis of each unit with the fixed length. The step of retrievingthe location data of the independent picture data includes the step ofdiscriminating the data type code recorded in the unit with the fixedlength, thereby selectively reproducing the independent picture dataalone.

In one embodiment, the data reproducing method uses the data recordingmedium in which a padding data is added to the independent picture dataso that the independent picture data to which the padding data is addedcompletes each unit with the fixed length, a valid data length fordiscriminating the padding data being recorded on the basis of each unitwith the fixed length. The step of retrieving the location data of theindependent picture data includes the step of detecting the valid datalength recorded in the unit with the fixed length, thereby reproducingthe independent picture data excluding the padding data.

In one embodiment, the data reproducing method uses the data recordingmedium in which the second pointer data is located at top and endportions of each of the AV files, the second pointer data including allthe second pointers corresponding to the first pointer data included inthe corresponding AV file. The step of reading out the second pointerdata comprises the steps of: reading the second pointer data recorded atthe top portion of the AV file, and when the second pointer datarecorded at the top portion of the AV file is unreadable, reading thesecond pointer data recorded at the end portion of the AV file; andreading the second pointer data at the end portion of the AV file, andwhen the second pointer data recorded at the end portion of the AV fileis unreadable, reading the second pointer data recorded at the topportion of the AV file.

In one embodiment, the data reproducing method uses the data recordingmedium in which the chapter data and the first pointer data arealternately located, and each of the first pointer data includes thefirst pointers corresponding to the independent picture data included inthe chapter data adjacent to that particular first pointer data, thefirst pointers include both prepointers storing the location data of theindependent picture data included in one of the chapter data locatedimmediately before the corresponding first pointer data and postpointersstoring the location data of the independent picture data included inone of the chapter data located immediately after the correspondingfirst pointer data. The step of reading out the first pointer datacomprises the steps of: reading the postpointers included in the nthfirst pointer data, and when the postpointers included in the nth firstpointer data are unreadable, reading the prepointers included in the(n+1)th first pointer data; and reading the prepointers included in thenth first pointer data, and when the prepointers included in the nthfirst pointer data are unreadable, reading the postpointers included inthe (n-1)th first pointer data.

The data recording medium of this invention is a medium having aplurality of units with a fixed length, and is used for recording AVfiles each including the video data that is compressed in units of apicture on the variable-bitrate condition. Each of the AV files recordedon the data recording medium includes a plurality of chapter dataincluding a plurality of GOP data, a plurality of first pointer dataeach having a plurality of first pointers, and at least one secondpointer data having a plurality of second pointers; each of the GOP dataincludes at least one picture data and at least one audio data; each ofthe first pointers is provided in a one-to-one correspondence to each ofthe audio data and stores location data of the corresponding audio data;each of the second pointers is provided in a one-to-one correspondenceto each of the first pointer data and stores location data of thecorresponding first pointer data; and a hierarchical location data forretrieving the audio data is formed by the first pointers and the secondpointers.

In one embodiment of the data recording medium according to thisinvention, each of the chapter data is arranged adjacent to one of thefirst pointer data including the first pointers corresponding to theaudio data included in that particular chapter data.

In one embodiment of the data recording medium according to thisinvention, the chapter data and the first pointer data are alternatelylocated, and each of the first pointer data includes the first pointerscorresponding to the audio data included in the chapter data adjacent tothat particular first pointer data.

In one embodiment of the data recording medium according to thisinvention, the second pointer data is located at the top portion and/orend portion of each of the AV files, and the second pointer dataincludes all of the second pointers corresponding to the first pointerdata included in the corresponding AV file, thereby storing the locationdata on all of the first pointer data included in the corresponding AVfile.

The data recording/reproducing apparatus of this invention uses arecording medium for recording and reproducing each unit with a fixedlength of a data. The apparatus comprises: a video data generatingcircuit for generating a compressed picture data byvariable-bitrate-compressing an externally input video signal in unitsof a picture; an audio data generating circuit for generating audio datafrom externally input audio signal; an interleaving circuit forgenerating GOP data by interleaving the compressed picture data and theaudio data on the basis of each unit with the fixed length, theinterleaving being performed in units of a picture group (GOP) includinga predetermined number of pictures, and generating a chapter dataincluding a plurality of the GOP data; a means for generating aplurality of first pointers, each first pointer being provided in aone-to-one correspondence to each of the audio data included in thechapter data so as to store a location data of the corresponding audiodata, and for generating a first pointer data by allocating theplurality of the first pointers in a predetermined order; a firstpointer data storing circuit for temporarily storing the first pointerdata; a means for generating a plurality of second pointers, each secondpointer being provided in a one-to-one correspondence to each of thefirst pointer data so as to store a location data of the correspondingfirst pointer data, and for generating a second pointer data byallocating the plurality of the second pointers in a predeterminedorder; a second pointer data storing circuit for temporarily storing thesecond pointers; a means for generating an AV file by alternatelyallocating the first pointer data and the chapter data and positioningthe second pointer data at a predetermined location; and a circuit forrecording the AV file on the data recording medium.

In one embodiment, the data recording/reproducing apparatus uses therecording medium in which the second pointer data includes all thesecond pointers corresponding to the first pointer data included in thecorresponding AV file, and the means for generating the AV fileallocating the second pointer data at top and/or end portions of each ofthe AV files.

The data recording/reproducing apparatus of this invention uses an datarecording medium having a plurality of units with a fixed length, inorder to record AV files each including the video data that iscompressed in units of a picture on the variable-bitrate condition, eachof the AV files including a plurality of chapter data including aplurality of GOP data, a plurality of first pointer data each having aplurality of first pointers, and at least one second pointer data eachhaving a plurality of second pointers; each of the GOP data including atleast one picture data and at least one audio data; each of the firstpointers being provided in a one-to-one correspondence to each of theaudio data and storing location data of the corresponding audio data;each of the second pointers being provided in a one-to-onecorrespondence to each of the first pointer data and storing locationdata of the corresponding first pointer data. The apparatus comprises apostrecording control means including: a means for reading the first andthe second pointer data from the data recording medium; a means fordetecting a location of the audio data by using the read first andsecond pointer data; and a circuit for recording input audio data at thedetected location.

In one embodiment of the data recording/reproducing apparatus of thepresent invention, the video data generating circuit and the audio datagenerating circuit add a data type code for discriminating the kind ofdata to be recorded to each unit with the fixed length.

In one embodiment of the data recording/reproducing apparatus of thepresent invention, the video data generating circuit and the audio datagenerating circuit add a padding data to each of the compressed picturedata and the audio data, and add a valid data length for discriminatingthe padding data to each unit with the fixed length in the compressedpicture data and the audio data.

The data recording/reproducing method according to this invention uses adata recording medium for recording/reproducing each unit with a fixedlength of data. The method comprises the steps of: generating acompressed picture data by variable-bitrate-compressing an externallyinput video signal in units of a picture; generating audio data fromexternally input audio signal; generating GOP data by interleaving thecompressed picture data and the audio data on the basis of each unitwith the fixed length, the interleaving being performed in units of apicture group (GOP) including a predetermined number of pictures;generating a chapter data including a plurality of the GOP data;generating a plurality of first pointers, each first pointer beingprovided in a one-to-one correspondence to each of the audio dataincluded in the chapter data so as to store location data of thecorresponding audio data and, generating a first pointer data byallocating the plurality of the first pointers in a predetermined order;temporarily storing the first pointer data; generating a plurality ofsecond pointers, each second pointer being provided in a one-to-onecorrespondence to each of the first pointer data so as to store locationdata of the corresponding first pointer data, and generating a secondpointer data by allocating the plurality of the second pointers in apredetermined order; temporarily storing the second pointers; generatingan AV file by alternately allocating the first pointer data and thechapter data and positioning the second pointer data at a predeterminedlocation; and recording the AV file on the data recording medium.

The data recording/reproducing method according to this invention uses adata recording medium having a plurality of units with a fixed length,in order to record/reproduce AV files each including the video data thatis compressed in units of a picture on the variable-bitrate condition,each of the AV files including a plurality of chapter data including aplurality of GOP data, a plurality of first pointer data each having aplurality of first pointers, and at least one second pointer data eachhaving a plurality of second pointers; each of the GOP data including atleast one picture data and at least one audio data; each of the firstpointers being provided in a one-to-one correspondence to each of theaudio data and storing location data of the corresponding audio data;each of the second pointers being provided in a one-to-onecorrespondence to each of the first pointer data and storing locationdata on the corresponding first pointer data. The method comprises apostrecording control step including the steps of: reading the first andthe second pointer data from the data recording medium; detectinglocation of the audio data by using the read first and second pointerdata; and recording an input audio data at the detected location.

In one embodiment, the data recording/reproducing method uses therecording medium in which the second pointer data includes all thesecond pointers corresponding to the first pointer data included in thecorresponding AV file, in the step of recording the AV file, the secondpointer data is allocated at the top and end portions of each AV file.The step of reading the second pointer data included in thepostrecording control step further includes the step of reading thesecond pointer data recorded at the end portion of the AV file when thesecond pointer data recorded at the top portion of the AV file isunreadable.

In one embodiment, the data recording/reproducing method uses therecording medium in which the audio pointers in the first pointer datainclude both prepointers storing the location data of the audio dataincluded in one of the chapter data located immediately before thecorresponding first pointer data and postpointers storing the locationdata of the audio data included in one of the chapter data locatedimmediately after the corresponding first pointer data. The step ofreading the first pointer data included in the postrecording controlstep comprises the step of: reading the postpointers included in the nthfirst pointer data, and when the postpointers included in the nth firstpointer data are unreadable, reading the prepointers included in the(n+1)th first pointer data.

Thus, the invention described herein makes possible the advantages of(1) providing a data recording medium having a data structure capable ofefficiently managing the location data on a plurality of I picture datalocated on the recording medium at unequal intervals; (2) providing adata reproducing apparatus and a data reproducing method for performinga trickplay mode operation such as fast forward reproducing and rewindreproducing by using the data recording medium; (3) providing a datarecording medium having a data structure capable of efficiently managingthe location data of a plurality of audio data recorded on the datarecording medium at unequal intervals by interleaving withvariable-bitrate-compressed video data in units of a sector; and (4)providing a data reproducing apparatus and a data reproducing method forconducting a postrecording operation by using the data recording medium.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the area structure of a data recording medium according toone example of the present invention;

FIG. 2 shows the data structure of an AV file and the hierarchicalstructure of global pointer data and picture pointer data formed on thedata recording medium of FIG. 1;

FIGS. 3A and 3B show examples of the data structure of a GOP data;

FIG. 4 shows the data structure in a physical sector;

FIG. 5 is a block diagram of the configuration of a data reproducingapparatus according to one example of this invention;

FIG. 6 is a block diagram of the configuration of a sub-codediscriminating circuit;

FIG. 7 is a flowchart for the processing procedures for a fast forwardreproducing operation by using the data reproducing apparatus of thepresent invention;

FIG. 8 is a flowchart for the processing procedures for a rewindreproducing operation by using the data reproducing apparatus of thepresent invention;

FIG. 9 is a block diagram of the configuration of a datarecording/reproducing apparatus according to one example of the presentinvention;

FIG. 10 is a block diagram of the configuration of an interleavingcircuit;

FIG. 11 is a flowchart for the processing procedures for an ordinaryrecording operation by using the data recording/reproducing apparatus ofthe present invention;

FIG. 12 shows the data structure of an AV file formed on a rewritabledata recording medium; and

FIG. 13 is a flowchart for the processing procedures for a postrecordingoperation by using the data recording/reproducing apparatus of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to the present invention, a data (information) recordingmedium storing AV files each including a video data that isvariable-bitrate-compressed in units of a picture, is used to conductfast forward reproducing and rewind reproducing at a high speed. In eachof the AV files recorded on the data recording medium of the presentinvention, an independent picture data is hierarchically managed by afirst pointer data (picture pointer data) having the location data ofthe independent picture data included in each chapter data and a secondpointer data (global pointer data) having the location data of the firstpointer data. In a data reproducing apparatus and a data reproducingmethod of the present invention, the location data of the independentpicture data is managed by using a hierarchical data structure, and thelocation data for a large number of the independent picture data locatedin the AV files at unequal intervals is efficiently retrieved withoutusing a bulk memory, thereby conducting the fast forward reproducing andthe rewind reproducing at a high speed.

Further, in the present invention, a data recording medium for storingAV files where audio data and variable-bitrate-compressed video data areinterleaved is used to conduct a postrecording operation. In each of theAV files recorded on the data recording medium, the audio data ishierarchically managed by a first pointer data (audio pointer data)having the location data of the audio data included in each chapter dataand a second pointer data (global pointer data). In the datarecording/reproducing apparatus and recording/reproducing method of thepresent invention, the location data of the audio data is managed byusing such a hierarchical data structure, and the location data for alarge number of the audio data located in the AV files at unequalintervals is efficiently managed without using bulk memory, therebyrealizing a postrecording operation in which the audio data alone isrewritten.

The data recording medium of the present invention, and the datarecording/reproducing apparatus and the data recording/reproducingmethod using the data recording medium will now be described referringto the accompanying drawings. The data recording/reproducing apparatusof the present invention is capable of a rapid trickplay mode operationsuch as fast forward reproducing and rewind reproducing of video data aswell as ordinary recording/reproducing operations, and can perform apostrecording operation in which audio data alone is rewritten.

EXAMPLE 1

FIG. 1 shows the area structure of a data recording medium 200 accordingto Example 1 of the present invention. The data recording medium 200 hasa data structure for rapidly conducting a trickplay mode operation. Onthe disk-shaped data recording medium 200 are formed a large number ofconcentrical or spiral tracks. Each track is divided into a large numberof sectors 201 each including a header field for storing an address dataand the like and a data field for storing user data of, for example,2048 bytes. In a read-only recording medium, both the header field andthe data field are pre-formatted during the production process of themedium. In a rewritable recording medium, the header field alone ispreliminarily formulated during the production.

In the data recording medium 200, a file recording area 202 is assignedto the outer tracks, and a file management area 203 is assigned to theinner tracks. The file recording area 202 stores a large number of AVfiles 210 each including a variable-bitrate-compressed video data. Thefile management area 203 stores file control data 220 for each AV file210, in which a volume name and the number of the stored AV files arerecorded at the leading portion followed by a large number of fileentries 221 each corresponding to each of the AV files 210. Each of thefile entries 221 includes a file related data such as the file name, thefile location and the file size of the corresponding AV file.

FIG. 2 shows the data structure of the AV file 210 shown in FIG. 1. Asis shown in FIG. 2, picture pointer data 230 and chapter data 240 arealternately located in the AV file 210, wherein the first and secondglobal pointer data 250 are located at the top and end portions,respectively. The global pointer data 250, the picture pointer data 230and the chapter data 240 are recorded in units of a sector, and theglobal pointer data 250 and the picture pointer data 230 can beindependently reproduced from the chapter data 240. In the AV file 210of this example, the global pointer data 250 is recorded at the top andend portions of the AV file 210, whereas it is possible to record theglobal pointer data 250 at one of the portions.

The chapter data 240 is a partial data of the AV file 210, and isgenerated by dividing the compressed video data, which is generated byvariable-bitrate-compressing the title as used in a movie in units of apicture, so as to achieve equal intervals of a constant display time(for example, 1 minute) or unequal intervals in accordance withrespective continuous scenes having a similar display picture quality.The chapter data 240 is further divided into a plurality of GOP (groupof pictures) data 260. Each of the GOP data 260 includes a compressedvideo data and a synchronized audio data with the video data, and in thecase of a movie title, further includes a text data for the subtitle tobe displayed simultaneously with the compressed video data. Thecompressed video data in each GOP data 260 includes one independentpicture data, which is intra-frame compressed as an I picture defined inthe MPEG standard as described in detail below. In conducting thetrickplay mode operation such as the fast forward reproducing and therewind reproducing, it is required to detect the location of theindependent picture data in order to selectively reproduce theindependent picture data.

As the video data is variable-bitrate-compressed, the locations of theindependent picture data are disposed on the recording medium at unequalintervals. In the recording medium of the present invention, thelocation data of each independent picture data is registered in apicture pointer data which is arranged immediately before and after theindependent picture data. Each of the picture pointer data 230 includes,as is shown in FIG. 2, a group of prepointers for managing all theindependent picture data included in the chapter data 240 arrangedimmediately before that particular picture pointer data 230 and a groupof postpointers for managing all the independent picture data includedin the chapter data 240 arranged immediately after that particularpicture pointer data 230.

The group of the prepointers is provided to the independent picturedata, and includes a plurality of prepointers 232 each storing thelocation data of the corresponding one of the independent picture dataand the number of the prepointers 232 included in the group of theprepointers (the number is recorded at the top portion of the group ofthe prepointers). Similarly, the group of the postpointers is providedto the independent picture data, and includes a plurality ofpostpointers 231 each storing the location data of the corresponding oneof the independent picture data and the number of the postpointers 231included in the group of the postpointers (the number is recorded at thetop portion of the group of the postpointers). In the followingdescription, when the prepointer 232 and the postpointer 231 are notdistinguished from each other, both are referred to as a picturepointer. It is noted that in the first picture pointer data 230 in eachAV file 210, the group of the postpointers alone is registered, and thatin the last picture pointer data 230 in each AV file 210, the group ofthe prepointers alone is registered.

The global pointer data 250 includes a plurality of global pointers 251corresponding to all the picture pointer data 230 which is included inone AV file 210. The location data of each of the picture pointer datasuch as a sector address is registered in the corresponding globalpointer 251.

Next, the exemplified structures of the GOP data 260 will be describedreferring to FIGS. 3A and 3B. Each GOP data 260 includes, as describedabove, the compressed video data, the audio data and the text datasynchronized with the video data. The compressed video data in each ofthe GOP data 260 includes one independent picture data 261 that isintra-picture (intra-flame or intra-field) compressed and dependentpicture data 262 that are inter-picture (inter-frame or inter-field)compressed, and is recorded using a plurality of sectors. For example,in accordance with the MPEG standard, the independent picture data 261corresponds to an I picture and the dependent picture data 262corresponds to a P picture and/or a B picture. The compression encodingof the data can be performed in units of a field. Further, the followingdescription in units of a picture is applicable to the compression inunits of a frame or a field.

The GOP data 260 shown in FIG. 3A is inter-leave-formatted, in which thevideo data (the independent picture data 261 and the dependent picturedata 262) and the audio data are interleaved in units of a sector. Theindependent picture data 261 is dividedly recorded in a plurality ofcontinuous areas (i.e., areas including a plurality of sectors) in eachGOP data 260. As the positional data for managing each independentpicture data 261, the corresponding picture pointer stores, for example,the top and last addresses of the area where the independent picturedata 261 and the audio data 263 are interleaved, or the start address ofthe interleaved area and the number of the sectors in the area.

The GOP data 260 shown in FIG. 3B is non-interleave-formatted, in whichthe video data (the independent picture data 261 and the dependentpicture data 262), the audio data and the text data are recorded on therespective continuous areas on the recording medium. As the positionaldata for managing the independent picture data 261 recorded at the topportion of each GOP data 260, the corresponding picture pointer stores,for example, the address of the leading sector of one continuous areastoring the independent picture data 261 and the number of the sectorsin the area.

In conducting the trickplay mode operation for the GOP data 260 which isnon-interleave-formatted as shown in FIG. 3B, the independent picturedata 261 can be easily discriminated so as to be reproduced since it isrecorded in one continuous area. On the other hand, the maximum timeinterval of reproducing the audio data 263 in ordinary operation becomeslonger as compared with the case of interleaved format as shown in FIG.3A, because the audio data 263 is also recorded in another continuousarea. Accordingly, in the ordinary reproducing operation, the capacityof an audio data buffer required for temporarily storing the audio data263 in the data reproducing apparatus becomes larger as compared withthe case where the GOP data is interleave-formatted. When theinterleave-formatted GOP data as shown in FIG. 3A is used, the capacityof the audio data buffer can be made smaller. In this case, however, thedata reproducing apparatus is required to comprise means fordiscriminating the interleaved independent picture data 261 and audiodata 263 in conducting the trickplay mode operation.

A specific example will now be described. When the location data of theindependent picture data is managed by using the aforementionedhierarchical management data structure, the capacity of the globalpointer data 250 and the picture pointer data 230 are calculated asfollows: In this calculation, it is assumed that each chapter data isconstructed from a video data for 1 minute in a movie title having areproducing time of, for example, 135 minutes. In this case, the globalpointer data 250 includes 135 global pointers 251. When an NTSC signalfor displaying 30 pictures for 1 second is compressed under thecondition of one GOP including 12 pictures, 150 prepointers 232 and 150postpointers 231 are registered in each picture pointer data 230. Wheneach of these pointers has, for example, a combination of the startaddress (an absolute value representation of four byte length) and thelast address (an offset representation of two byte length) of the areawhere the independent picture data 261 and the audio data 263 areinterleaved, the picture pointer data 230 has a capacity of 1,800 bytes,and is recorded by using one 2 KB sector. When it is assumed that theglobal pointer 250 indicating the location data of the picture pointerdata has a sector address (four byte length representation) alone, thecapacity thereof is 540 bytes. The global pointer data 250 is recordedon the medium using one sector. Further, in this case, the memorycapacity required for temporarily storing the global pointer data 250and the picture pointer data 230, which are read from the recordingmedium to retrieve the location of the independent picture data 261, is4 KB (corresponding to two sectors). Thus, the buffer capacity of 80 KBdescribed in the related art can be largely decreased.

FIG. 4 shows the data structure of the sector 201, which is a basic unitfor performing the recording/reproducing operation using the datarecording medium 200. As shown in FIG. 4, the sector 201 includes aheader field and a data field. In the header field, the address data ofthe sector 201 such as ID0 and ID1 are multiply recorded. The data fieldincludes a sub-code field 204, a user data field 205 and an errorcorrection code (ECC) field 206.

The ECC field 206 stores an error correction code using, for example, aReed-Solomon code for protecting the data in the sub-code field 204 andthe user data field 205 from having an error on the recording medium.The user data field 205 stores control data such as the global pointerdata 250 and the picture pointer data 230 and various data elements suchas the video data which includes the independent picture data 261, thedependent picture data 262, the audio data 263 synchronized with thevideo data, and the text data 264 to be displayed simultaneously withthe video data. The sub-code field 204 stores a data type code 207 fordiscriminating the contents of the user data with any of the controldata, the video data, the audio data and the text data.

When each GOP data 260 is interleave-formatted as is shown in FIG. 3A,the data reproducing apparatus discriminates the interleaved independentpicture data 261 from the audio data 263 by using the data type code207, and selectively reproduces the independent picture data alone inthe trickplay mode operation. Furthermore, when a padding data is addedat the end of the user data field 205, the sub-code field 204 alsostores a valid data length 208 and the like of the element data which isrecorded in the user data field 205 with a fixed length. The valid datalength 208 indicates the length of the element data excluding thepadding data.

Although the global pointers 251 are recorded as the global pointer data250 located at the top and/or end portions of each AV file 210 in thisexample, it is possible to locate the global pointers in anotherportion. For example, the global pointer data 250 can be plurallydivided so as to be recorded together with the predetermined one of thepicture pointer data 230.

As described above, in the data recording medium 200 of Example 1, thelocations of the independent picture data located at unequal intervalsare managed by using the hierarchical management data including thepicture pointer data 230 for managing the location data of therespective independent picture data and the global pointer data 250 formanaging the location data of the respective picture pointer data 230.When the data reproducing apparatus performs the trickplay modeoperation using this recording medium 200, this apparatus never requiresa bulk memory to store all the location data of the independent picturedata. Accordingly, the data reproducing apparatus can attain a rapidtrickplay mode operation by retrieving the locations of the respectiveindependent picture data in a step-wise manner using memory circuitshaving a small capacity.

EXAMPLE 2

FIG. 5 shows an example of a data reproducing apparatus 300 forconducting a data reproducing operation in units of a sector using thedata recording medium 200 described in Example 1. As is shown in FIG. 5,the data reproducing apparatus 300 comprises a disk drive unit 10, adata reproducing circuit 11, a sub-code discriminating circuit 12, acontrol data buffer 13, a video data buffer 17, an audio data buffer 18,a text data buffer 19, a video decoder circuit 20, a charactergenerating circuit 21, a video overlaying circuit 22, an audio decodercircuit 23, a front panel 24, and a microcontroller 25.

The disk drive unit 10 rotates the disk-shaped data recording medium 200contained therein, and detects a certain sector 201 by moving theself-contained head (not shown) so as to read signals from the datafield in the sector. Then, the disk drive unit 10 conducts signalprocessing such as amplification and binarization and outputs the thusobtained reproducing signal 100 to the data reproducing circuit 11. Thedata reproducing circuit 11 performs demodulation and error correctionupon the reproducing signal 100 in units of a sector and transfers thethus obtained reproducing data 101 to the sub-code discriminationcircuit 12. The reproducing data 101 includes the contents recorded inthe sub-code field 204 and the user data field 205 as mentioned abovewith reference to FIG. 4. The sub-code discriminating circuit 12interprets the sub-code contained in the reproducing data 101 todiscriminate the data type code 207. Further, the sub-codediscriminating circuit 12 removes the padding data by using the validdata length 208 stored in the sub-code field 204, and transfers the thusobtained control data 102, video data 103, audio data 104 and text data105 to the corresponding circuits in accordance with the result of thedata type code 207. In conducting the trickplay mode operation, thesub-code discrimination circuit 12 transfers only the user data having aspecific data type code such as the independent picture data 261.

The control data buffer 13 is a memory circuit for temporarily storingthe control data 102 transferred by the sub-code discriminating circuit12, and is used dividedly as a file control data buffer 14, a globalpointer buffer 15 and a picture pointer read buffer 16. The video databuffer 17, the audio data buffer 18, and the text data buffer 19 arememory circuits for temporarily storing the video data 103, the audiodata 104, and the text data 105 transferred by the sub-codediscriminating circuit 12, respectively.

The video decoder circuit 20 reads out the video data 103 from the videodata buffer 17 for decoding so as to generate a reproducing picturesignal 106. The character generating circuit 21 reads out the text data105 from the text data buffer 19 so as to convert it into a text displaysignal 107. The video overlaying circuit 22 generates a videoreproducing signal 108 by logically adding the reproducing picturesignal 106 to the text display signal 107, and transfers the videoreproducing signal 108 to an external video output apparatus such as aTV monitor. The audio decoder circuit 23 reads out the audio data 104from the audio data buffer 18 for decompression, and transfers the thusgenerated audio reproducing signal 109 to an external audio outputapparatus such as a loudspeaker.

The front panel 24, in a similar manner to the selection means in a CDplayer, selects a certain AV file specified by an operator among a largenumber of the AV files recorded on the data recording medium andcontrols the start and the stop of the reproducing operation. The frontpanel 24 is also used as a means for setting the reproducing operationmode such as the ordinary reproducing, the fast forward reproducing andthe rewind reproducing. The microcontroller 25 controls the entire datareproducing apparatus 300 in accordance with an operation mode controlsignal 110 output from the front panel 24.

In the data reproducing apparatus having the aforementionedconfiguration, the operator selects the AV files and sets the operationmode through the front panel 24. When the data reproducing apparatus 300is connected with a computer as a peripheral device like a CD-ROM driveunit, however, it is possible to select the AV files and set theoperation mode by the host computer through a host interface circuitsuch as a SCSI control circuit.

FIG. 6 is an example of the configuration of the sub-code discriminatingcircuit 12 shown in FIG. 5. As shown in FIG. 6, the sub-codediscriminating circuit 12 comprises a data type discriminating circuit40, a data length detecting circuit 41, and a data transfer controlcircuit 42. The data type discriminating circuit 40 receives thereproducing data 101, discriminates the data type code 207 recorded inthe sub-code field 204, and outputs a data type signal 120 to the datatransfer control circuit 42. Similarly, the data length detectingcircuit 41 receives the reproducing data 101, discriminates the validdata length 208 recorded in the sub-code field 204, and outputs a datacount control signal 121 to the data transfer control circuit 42.

The data transfer control circuit 42 comprises a counter circuit, aselector circuit and the like, and controls the data transfer operationof the user data in accordance with the state of the reproducing modecontrol signal 111 which is set through the microcontroller 25. When theordinary reproducing operation mode is set by the reproducing modecontrol signal 111, the data transfer control circuit 42 controls theselector circuit therein in accordance with the received data typesignal 120, and also controls the counter circuit therein in accordancewith the received data count control signal 121, thereby transferringany effective data among the control data 102, the video data 103, theaudio data ta 104, and the text data 105 to the related circuits. Whenthe transfer of data in an amount set by the data count signal 121 iscompleted, the data transfer control circuit 42 outputs a data transferend signal 112 to the microcontroller 25, thereby terminating the datatransfer operation.

Basic processing procedures for the data reproducing operation using thedata reproducing apparatus 300 having the aforementioned configurationwill now be described. When the control data 102 such as the filecontrol data 220, the global pointer data 250, or the picture pointerdata 230 are reproduced, the microcontroller 25 sets, in the disk driveunit 10, an address indicating the location of the control data 102 onthe recording medium as a drive control signal 113. When the disk driveunit 10 finishes its seek operation, the microcontroller 25 sets, in thesub-code discriminating circuit 12, the reproducing mode control signal111 indicating the ordinary reproducing operation. Further, in order toset an area where the control data 102 is recorded in the datareproducing circuit 11, the microcontroller 25 outputs the start addressand the number of sectors of the area to be read out in the datareproducing circuit 11 as a reproducing operation control signal 114.The data reproducing circuit 11 discriminates the address signalrecorded in the header field of each sector from the reproducing signal100 and demodulates it, and detects whether or not the address matcheswith the address of the sector specified as the area to be reproduced.When the addresses are detected in order to be matched, the datareproducing circuit 11 demodulates and conducts the error correction forthe reproducing signal 100 read from the data field, thereby generatingthe reproducing data 101. The data reproducing circuit 11 outputs to themicrocontroller 25 a reproducing status signal 115 indicating whetherthe data reproducing of the specified area is normally finished or isabnormally finished because of the detection of an uncorrectable errordue to a flaw on the recording medium or the like. When the reproducingoperation is normally finished, the sub-code discriminating circuit 12detects the data type code 207 and the valid data length 208 from thesub-code data included in the reproducing data 101. When the sub-codediscriminating circuit 12 determines the contents of the user data 205to be the control data 102 based on the data type code 207, the controldata buffer 13 is set as the circuit for receiving the data, and theuser data specified by the valid data length 208 (i.e., the user dataexcluding the padding data) is transferred to the control data buffer13.

Next, the reproducing operation of the independent picture data 261 inthe fast forward reproducing and the rewind reproducing will bedescribed. The microcontroller 25 calculates the location of theindependent picture data 261 by using the file control data 220, theglobal pointer data 250, and the picture pointer data 230 that waspreviously read out in the control data buffer 13. Then, themicrocontroller 25 executes the seek operation in the same manner as inthe reproducing operation for the control data 102. Next, themicrocontroller 25 sets, in the sub-code discriminating circuit 12, thereproducing mode control signal 111 which instructs the selectivereproduction of the independent picture data 261. Further, in order toset in the data reproducing circuit 11, a recording area of theindependent picture data 261, the microcontroller 25 outputs the startaddress and the number of sectors of the area to be reproduced as thereproducing operation control signal 114. The data reproducing circuit11 continuously conducts the demodulation and the error correction ofall the sectors in the area that is determined to be reproduced, andtransfers the reproducing data 101 to the sub-code discriminatingcircuit 12. The data type discriminating circuit 40 and the data lengthdetecting circuit 41 in the sub-code discriminating circuit 12 detectthe data type code 207 and the valid data length 208 from thereproducing data 101, and output the data type signal 120 and the datacount control signal 121, respectively. When the data transfer controlcircuit 42 determines that the reproducing data 101 is the independentpicture data based on the data type signal 120, the video data buffer 17is set as the circuit for receiving the data, and the video data 103specified by using the valid data length is transferred to the videodata buffer 17.

Generally, when video data corresponding to an NTSC-TV signal iscompressed, the capacity of the independent picture data 261 exceeds 100KB. Therefore, in the reproducing operation of the independent picturedata 261, the demodulation, the error correction, and the data transferfor a large number of the sectors are executed in parallel as pipelineprocessing, while discrimination of the data type code 207 and the validdata length 208 is performed. Further, when the trickplay mode operationis performed by using the recording medium as shown in FIG. 3A in whichthe independent picture data 261 and the audio data 263 are recorded inan interleave format in units of a sector, the sub-code discriminatingcircuit 12 can discriminate alone that is the independent picture data261 that is to be transferred to the video data buffer 17 as describedabove.

Next, the processing procedures for the fast forward reproducing and therewind reproducing by the data reproducing apparatus 300 using the datarecording medium 200 having the data structure as shown in FIGS. 1 and 2will be described. Here, it is assumed, for simplification, that the AVfile 210 to be reproduced includes three chapter data 240 and that eachof the chapter data 240 includes four GOP data 260. It is also assumedthat the contents of the four picture pointer data 230 including thelocation data of the respective independent picture data 261 are set aslisted in Table 1.

                  TABLE 1                                                         ______________________________________                                                    Prepointers Postpointers                                          ______________________________________                                        Picture Pointer                                                                             ( Unused )    Address (P 1)                                     Data 1        ( Unused )    Address (P 2)                                                   ( Unused )    Address (P 3)                                                   ( Unused )    Address (P 4)                                     Picture Pointer                                                                             Address (P 1) Address (P 5)                                     Data 2        Address (P 2) Address (P 6)                                                   Address (P 3) Address (P 7)                                                   Address (P 4) Address (P 8)                                     Picture Pointer                                                                             Address (P 5) Address (P 9)                                     Data 3        Address (P 6) Address (P 1 0)                                                 Address (P 7) Address (P 1 1)                                                 Address (P 8) Address (P 1 2)                                   Picture Pointer                                                                             Address (P 9) ( Unused )                                        Data 4        Address (P 1 0)                                                                             ( Unused )                                                      Address (P 1 1)                                                                             ( Unused )                                                      Address (P 1 2)                                                                             ( Unused )                                        ______________________________________                                    

FIG. 7 is a flowchart for the processing procedures for the fast forwardreproducing performed by the data reproducing apparatus 300 using the AVfile 210 having the aforementioned structure. The specific reproducingprocedures will be described in accordance with the processingprocedures (steps) shown in the flowchart. In the following description,it is assumed that the file control data 220 recorded on the datarecording medium 200 has already been read out and stored in the filecontrol data buffer 14, in accordance with the above-mentionedprocessing procedures when the recording medium was loaded in the diskdrive unit 10 or reset.

(S701) An operator starts the reproducing operation by selecting an AVfile 210 to be reproduced by using the front panel 24, and determinesthe operation mode for the fast forward reproducing from the start ofthe file. At this point, it is assumed that the fast forward reproducingspeed is set so that every other piece of the independent picture data261 are successively reproduced, i.e, in the order of the first, thethird, the fifth, etc. (i.e., in an ascending order of odd numbers).Such a reproducing condition is supplied to the microcontroller 25 asthe operation mode control signal 110 to be set.

(S702) The microcontroller 25 retrieves the location of the specified AVfile 210 from the file control data in the file control data buffer 14.The microcontroller 25 executes the reproducing operation of the firstglobal pointer data 250 recorded at the top portion of the AV file 210in accordance with the same procedure as used for the file control data220 described above. When this data reproducing operation is normallycompleted, the global pointer data 250 is stored in the global pointerbuffer 15.

(S703) When the detection of an uncorrectable error is informed from thedata reproducing circuit 11 in the step S702, the microcontroller 25executes, as a recovery process, the reproducing operation of the secondglobal pointer data 250 recorded at the end portion of the AV file 210in accordance with the same procedure as used in the step S702.

(S704) In order to execute the fast forward reproducing operation fromthe top of the file, the microcontroller 25 retrieves the location of apicture pointer data 230(1) from the global pointer data 250. Then, themicrocontroller 25 executes the reproducing operation of the picturepointer data 230(1). When this data reproducing operation is normallycompleted, the picture pointer data 230(1) is stored in the picturepointer read buffer 16.

(S705) The microcontroller 25 searches and retrieves the location of theindependent picture data 261 for displaying from the postpointers 231 ofthe reproduced picture pointer data 230. Specifically, under thisreproducing condition, an address P1 is detected as the postpointer 231in the first searching operation, and address P5, P9 and the like aredetected in the subsequent searching operations (See Table 1).

(S706) When the detection of an uncorrectable error is informed from thedata reproducing circuit 11 in the step S704, as the recovery process,the microcontroller 25 executes the reproducing operation of a picturepointer data 230(2) which is the subsequent picture pointer data, inaccordance with the same procedure as used in the step S704 (See Table1).

(S707) The microcontroller 25 searches and retrieves the location of theindependent picture data 261 for displaying from the prepointers 232 ofthe picture pointer data 230(2). Specifically, under this reproducingcondition, the address P1 is detected as the prepointer 232 in the firstsearching operation, and the addresses P5, P9 and the like are detectedin the subsequent searching operations (See Table 1).

(S708) When the location of the independent picture data 261 isdetected, the microcontroller 25 stores video data 103 in the video databuffer 17 in accordance with the above-mentioned processing procedures.Next, the video decoder circuit 20 reads out the compressed video datafrom the video data buffer 17 for decompression. The reproducing picturesignal 106 generated in the video decoder circuit 20 is output to theoutside through the video overlaying circuit 22. The video decodercircuit 20 repeats the outputting and displaying the same expanded imageuntil the subsequent independent picture data 261 is read out into thevideo data buffer 17. For example, in the case of an NTSC signal fordisplaying 30 pictures per 1 second, when the time required for thesubsequent independent picture data 261 to be read out into the videodata buffer 17 is at most 100 ms, the video decoder circuit 20 repeatsdisplaying the same independent picture data 261 three times.

(S709) The microcontroller 25 detects whether or not a stop key providedon the front panel 24 is pushed (i.e., a stop command is input), andwhen pushed, the reproducing operation is terminated. Further, when themicrocontroller 25 retrieves all the picture pointers to be searched,the microcontroller 25 detects that the AV file 210 is fast forwardreproduced to the end and terminates this operation.

(S710) When the reproducing operation is not terminated in step S709,the microcontroller 25 searches and retrieves the postpointer 231 or theprepointer 232 corresponding to the subsequent independent picture data261 in the picture pointer read buffer 16. In this explanation of theoperation, the reproducing speed is set so that every other piece of theindependent picture data 261 is successively displayed. Therefore, forexample, when the address P1 is detected in step S705, themicrocontroller 25 searches and retrieves the address P3 as thesubsequent postpointer 231 or prepointer 232. When the subsequentpicture pointer is detected, the microcontroller 25 executes thereproducing and displaying operations of the independent picture data261 starting from the address P3 by returning to the step S708. When,for example, the address P3 is detected as the postpointer 231 in thestep S705, the address P5, that is, the subsequent postpointer 231, isnot included in the picture pointer data 230(1) which has been stored inthe picture pointer read buffer 16. In this case, the microcontroller 25executes the reproducing operation of the subsequent picture pointerdata 230(2) by returning to the step S704 (See Table 1).

(S711) When the reproducing operations of the global pointer data 250 orthe picture pointer data 230 are not normally completed in the stepsS703 or the step S706, respectively, the microcontroller 25 suspends thefast forward reproducing operation and displays a data reproducing errormessage.

As described above, the data reproducing apparatus 300 of the presentinvention performs fast forward reproducing operations by previouslyreading out the global pointer data 250 and the picture pointer data 230in the memory circuits, and successively reproducing and displaying theindependent picture data 261 alone while retrieving the data in thememory circuits. In the step S708, 100 ms after displaying the nthindependent picture data 261, the (n+2)th independent picture data 261is displayed. That is to say, when a GOP includes 12 pictures, thepicture located 24 pictures behind is displayed. Under this condition,one independent picture data 261, which is to be displayed 800 ms after(in the case of an NTSC signal) in the ordinary reproducing operationmode, is displayed 100 ms after, and hence, the fast forward reproducingoperation is performed at a speed eight times as high as the ordinaryreproducing. The reproducing speed in such a fast forward reproducingoperation can be adjusted with ease by controlling the interval betweenthe independent picture data 261 to be displayed and the number ofrepeat times of displaying each independent picture data 261 related tothe interval.

In order to attain a higher speed of the fast forward reproducing, forexample, the nth independent picture data is displayed for 100 ms, andthen the (n+4)th independent picture data is displayed. Thus, the speedbecomes 16 times as high as the ordinary reproducing. On the other hand,in order to attain a lower speed of the fast forward reproducing, forexample, the entire independent picture data 261 are displayed atintervals of 100 ms each. Thus, the speed is decreased in order to befour times as fast as ordinary reproducing. Further, when the number ofrepeat times of displaying the independent picture data 261 isdecreased, the fast forward reproducing speed is increased, and when thenumber is increased, the speed is decreased. As described above withreferring to FIG. 3, each picture pointer data 230 includes, forexample, 150 prepointers 232 and 150 postpointers 231. Accordingly, whenthe fast forward reproducing speed is varied while displaying an image,or when an uncorrectable error is detected in the independent picturedata 261, such a state can be dealt with by changing the retrievingcondition of the picture pointer data 230 through the microcontroller25. For example, when an error is detected in one independent picturedata 261, the microcontroller 25 can easily execute an error recoveryprocess so that the subsequent independent picture data 261 is displayedinstead.

Next, the processing procedures for the rewind reproducing by the datareproducing apparatus 300 using the AV file 210 having the datastructure of the picture pointer data 230 as listed in Table 1 will bedescribed with referring to a flowchart shown in FIG. 8. Also in thefollowing description, it is assumed that the file control data 220 havealready been read out and stored in the file control data buffer 14, inaccordance with the aforementioned processing procedures.

(S801) The operator starts the reproducing operation by selecting an AVfile 210 for reproducing through the control panel 24, and determinesthe operation mode for the rewind reproducing from the end of the file.At this point, it is assumed that the rewind reproducing speed is set sothat every other pieces of the independent picture data have beensuccessively reproduced in the order of the last data, the last but two,the last but four, etc. Such a reproducing condition is set in themicrocontroller 25 as the operation mode control signal 110.

(S802) The microcontroller 25 searches and retrieves the location of thespecified AV file 210 from the file control data in the file controldata buffer 14. The microcontroller 25 executes the reproducingoperation of the second global pointer data 250 recorded at the endportion of the AV file 210. When this data reproducing operation isnormally completed, the global pointer data 250 is stored in the globalpointer buffer 15.

(S803) When the detection of an uncorrectable error is informed from thedata reproducing circuit 11 in the step S802, the microcontroller 25executes, as a recovery process, the reproducing operation of the firstglobal pointer data 250 recorded at the top portion of the AV file 210in accordance with the same procedure as used in the step S802.

(S804) In order to execute the rewind reproducing operation from the endof the file, the microcontroller 25 searches and retrieves the locationof a picture pointer data 230(4) from the global pointer data 250. Then,the microcontroller 25 executes the reproducing operation of the picturepointer data 230(4). When this data reproducing operation is normallycompleted, the picture pointer data 230(4) is stored in the picturepointer read buffer 16.

(S805) The microcontroller 25 searches and retrieves the location of theindependent picture data 261 for displaying from the prepointers 232 ofthe reproduced picture pointer data 230(4). Specifically, under thisreproducing condition, an address P12 is detected as the prepointer 232in the first-searching operation, and addresses P8, P4 and the like aredetected in the subsequent searching operations (See Table 1).

(S806) When the detection of an uncorrectable error is informed from thedata reproducing circuit 11 in the step S804, as the recovery process,the microcontroller 25 executes the reproducing operation of a picturepointer data 230(3) which is the subsequent picture pointer data, inaccordance with the same procedure as used in the step S804 (See Table1).

(S807) The microcontroller 25 searches and retrieves the location of theindependent picture data 261 for displaying from the postpointers 231 ofthe picture pointer data 230(3). Specifically, under this reproducingcondition, the address P12 is detected as the postpointer 231 in thefirst searching operation, and the addresses P8, P4 and the like aredetected in the subsequent searching operations (See Table 1).

(S808) When the location of the independent picture data 261 isdetected, the microcontroller 25 stores the video data 103 in the videodata buffer 17 in accordance with the above-mentioned processingprocedures. Next, the video decoder circuit 20 reads out the compressedvideo data from the video data buffer 17 for decompression. Thereproducing picture signal 106 generated in the video decoder circuit 20is output to the outside through the video overlaying circuit 22 to bedisplayed. The video decoder circuit 20 repeats outputting anddisplaying the same expanded image until the subsequent independentpicture data 261 is read out into the video data buffer 17. For example,in the case of an NTSC signal for displaying 30 pictures per 1 second,when the time required for the subsequent independent picture data 261to be read out into the video data buffer 17 is at most 100 ms, thevideo decoder circuit 20 repeats displaying the same independent picturedata 261 three times.

(S809) The microcontroller 25 detects whether or not the stop keyprovided on the front panel 24 is pushed (i.e., a stop command isinput), and when pushed, the reproducing operation is terminated.Further, when the microcontroller 25 retrieves all the picture pointersto be searched, the microcontroller 25 detects that the AV file 210 isrewind and reproduced to the top and terminates this operation.

(S810) When the reproducing operation is not terminated in step S809,the microcontroller 25 searches and retrieves the prepointer 232 or thepostpointer 231 corresponding to the subsequent independent picture data261 in the picture pointer read buffer 16. In this explanation of theoperation, the reproducing speed is set so that every other piece of theindependent picture data 261 are successively displayed. Therefore, forexample, when the address P12 is detected in step S805, themicrocontroller 25 searches and retrieves the address P10 as thesubsequent prepointer 232 or postpointer 231. When the subsequentpicture pointer is detected, the microcontroller 25 executes thereproducing and displaying operations of the independent picture data261 starting from the address P10 by returning to step S808. When, forexample, the address P10 is detected as the prepointer 232 in the stepS805, an address P8, that is, the subsequent prepointer 232, is notincluded in the picture pointer data 230(4) which has been stored in thepicture pointer read buffer 16. In this case, the microcontroller 25executes the reproducing operation of the subsequent picture pointerdata 230(3) by returning to the step S804 (See Table 1).

(S811) When the reproducing operations of the global pointer data 250 orthe picture pointer data 230 are not normally completed in the stepsS803 or the step S806, respectively, the microcontroller 25 suspends therewind reproducing operation and displays a data reproducing errormessage.

As described above with reference to FIG. 8, the data reproducingapparatus 300 of the present invention executes the rewind reproducingby previously reading out the global pointer data 250 and the picturepointer data 230 in the memory circuits, and retrieving the read pointerdata in order to determine the location of the independent picture data261, thereby successively reproducing and displaying the independentpicture data 261 alone from the end of the AV file 210. The reproducingspeed of such a rewind operation can be, similarly to the fast forwardoperation described above, made faster or slower by controlling theinterval between the independent picture data 261 for displaying or thenumber of the repeat times of displaying each respective independentpicture data 261. Further, it is apparent that the change of thereproducing speed during the display and the detection of anuncorrectable error in the independent picture data can be dealt withsimilarly to the case of the fast forward reproducing.

The above described fast forward reproducing and rewind reproducing areexecuted by using the AV file having the data structure as shown in FIG.2 in which the global pointer data 250 and the picture pointer data 230are doubly recorded. The data reproducing apparatus 300 can, however,perform the trickplay mode operation by using a recording medium inwhich the global pointer data 250 and the picture pointer data 230 arenot multiply recorded. For example, when the rewind reproducing isperformed by using a recording medium where the postpointers 231 aloneare recorded, the microcontroller 25 performs the procedure in the stepS806 while always regarding that an uncorrectable error is detected instep S804. Thus, it is possible to read the postpointers 231 requiredfor the retrieval. Similarly, it is also possible to perform the fastforward reproducing by using a recording medium where the prepointers232 alone are recorded. When a recording medium where the global pointerdata 250 and the picture pointer data 230 are not doubly recorded isused, however, the microcontroller 25 cannot perform the error recoveryoperation described in the steps S703 and S706. Accordingly, when thecontrol data 102 stored in such a recording medium includes anuncorrectable error, it is impossible to display the entire AV file 210or the entire chapter data 240 in the trickplay mode operation.

In each of the AV files 210, the doubly recorded global pointer data 250and picture pointer data 230 are used for both the purpose of conductingthe trickplay mode operation normally and performing the error recovery.Specifically, the first global pointer data 250 and the postpointers 231in each picture data 230 are used not only for the normal fast forwardreproducing but also for the error recovery in the rewind reproducing.The second global pointer data 250 and the prepointers 232 are used forboth the normal rewind reproducing and the error recovery in the fastforward reproducing. In this manner, the global pointer data 250 and thepostpointers 231 for the fast forward (forward direction) reproducingand the global pointer data 250 and the prepointers 232 for the rewind(reverse direction) reproducing are separately provided. Accordingly,required data can be retrieved without going backward and jumping intothe respective reproducing operations, resulting in easy control of theretrieval and efficient trickplay mode.

In conventional double recording used for general error recovery, theaddress data are doubly recorded, for example, by using two continuousareas as in the header field shown in the sector format of FIG. 4. Thistype of double recording may result in insufficient reliability of thestored data, since, for example, both data of these two areas aredefective when one defect occurs on the boundary between the two areas.In order to cover this disadvantage, if the same data are triplyrecorded or an error detection code is added, the capacity overhead isapparently increased. The double recording of the global pointer data250 and the picture pointer data 230 in the present invention is largelydifferent from this conventional technique in the following two points:First, although these pointers are disposed mainly for efficientlycontrolling the fast forward reproducing and the rewind reproducing,they also usefully serve for conducting the error recovery. Secondly,these doubly recorded pointers are dispersedly recorded on differentareas on the recording medium, the reliability of the stored data iscomparatively higher than in the conventional double recordingtechnique. Thus, the double recording of the pointer data in the presentinvention is practically effective both in the trickplay mode operationand the error recovery operation.

On the other hand, the chapter data has a much larger capacity than thepointer data, and hence, the double recording of the chapter data is notpractical. Accordingly, when an uncorrectable error is detected inreproducing the independent picture data 261, the data reproducingapparatus 300 works as follows: When an uncorrectable error is detected,the data reproducing circuit 11 informs the microcontroller 25 of theoccurrence of the error without transferring the reproducing data 101.At this point, the microcontroller 25 informs the video decoder circuit20 of the detection of the error in the video data to be transferred tothe video data buffer 17, and simultaneously suspends reproducing theindependent picture data 261 including the error, and starts reproducingthe subsequent independent picture data 261. The video decoder circuit20 repeatedly outputs and displays the presently displayed image untilthe subsequent independent picture data 261 is read out in the videodata buffer 17. Thus, the independent picture data 261 including theerror is not displayed but skipped. Accordingly, although the smoothnessof the video is partly spoiled, the trickplay mode operation is executedwithout being suspended.

As described above, in the data reproducing apparatus 300 and thereproducing method using the data reproducing apparatus 300 of thepresent invention, the locations of the independent picture datadisposed at unequal intervals are retrieved and reproduced by using thehierarchical management data including the global pointer data 250 andthe picture pointer data 230. Therefore, the data reproducing apparatus300 never requires a bulk memory to store all the location data of theindependent picture data 261 in the trickplay mode operation. Thus, itis possible to retrieve the locations of the respective independentpicture data in a stepwise manner by using the memory circuits withsmall capacity, thereby performing a rapid trickplay mode operation.

Further, the global pointer data 250 is doubly recorded by using thefirst and the second global pointer data at the top and the end portionsof each AV file, and the picture pointer data 230 is doubly recorded byusing the postpointers 231 and the prepointers 232. When an error occursin one of the doubly recorded data, the other is used for the trickplaymode operation, thereby largely enhancing the error recovery functionwithout largely increasing the data capacity.

EXAMPLE 3

Next, a data recording/reproducing apparatus having a postrecordingfunction for rewriting an audio data alone and a datarecording/reproducing method by using the apparatus will be describedreferring to the accompanying drawings. FIG. 9 is a block diagramshowing an exemplifying configuration of a data recording/reproducingapparatus 400 performing a data recording/reproducing operation by usinga data recording medium in which data are recorded and reproduced inunits of a sector. As is shown in FIG. 9, in the datarecording/reproducing apparatus 400, the configuration of a block fromthe disk drive unit 10 to the microcontroller 25 is identical to that ofthe data reproducing apparatus 300 shown in FIG. 5. The datarecording/reproducing apparatus 400 further comprises a video encodercircuit 32, an audio encoder circuit 33, an interleaving circuit 34 anda data recording circuit 35. The control data buffer 13 is furtherdivided so as to work as a picture pointer write buffer 27, an audiopointer read buffer 28, and an audio pointer write buffer 29 as well asthe file control data buffer 14, the global pointer buffer 15 and thepicture pointer read buffer 16.

The video encoder circuit 32 performs variable-bitrate-compression on anexternally input video recording signal 130 in units of a picture. Then,the video encoder circuit 32 adds, in accordance with the sector formatshown in FIG. 4, the sub-code data 204 including the data type code 207and the valid data length 208 and the padding data, if necessary, to thecompressed data, thereby generating a compressed picture data 131 havinga data size integral times as large as the sector length. The audioencoder circuit 33 compresses an externally input audio recording signal132, and adds the sub-code data 204 and the padding data, if necessary,to the compressed data, thereby generating a compressed audio data 133having a data size an integral number times as large as the sectorlength. The thus generated compressed picture data 131 and compressedaudio data 133 are temporarily stored in the video data buffer 17 andthe audio data buffer 18, respectively in units of a sector. Theinterleaving circuit 34 reads out the compressed picture data 131 andthe compressed audio data 133 included in one GOP in units of a sector,and performs an interleaving process in accordance with a predeterminedalgorithm, thereby generating the GOP data 260 having the format asshown in FIG. 3A or 3B. Then, the GOP data 260 is transferred to thedata recording circuit 35 as one of recording data 134. Further, theinterleaving circuit 34 transfers to the microcontroller 25 aninterleave data 135 indicating the location of the audio data 263 andthe independent picture data 261 in the GOP data 260 during theinterleaving process. The audio pointer write buffer 29 and the picturepointer write buffer 27 temporarily store an audio pointer data 430 anda picture pointer data 230 generated by the microcontroller 25 inaccordance with the interleave data 135, respectively. The audio pointerread buffer 28 temporarily stores the audio pointer data 430 read outfrom the recording medium. The data recording circuit 35 adds an errorcorrection code to the recording data 134 and modulates the resultantdata to be output as a recording signal 136. The recording data 134includes not only the GOP data 260 but also the control data 102transferred from the control data buffer 13. Accordingly, the selectorcircuit in the interleaving circuit 24 switches the contents of therecording data 134 to be transferred in accordance with a data switchingsignal 137 input from the microcontroller 25.

FIG. 10 is a block diagram showing an exemplified configuration of theinterleaving circuit 34 shown in FIG. 9. As is shown in FIG. 10, theinterleaving circuit 34 comprises an AV interleaving circuit 51 and apointer interleaving circuit 52.

The AV interleaving circuit 51 contains a microprocessor and the like(not shown) for executing the interleaving process of the compressedpicture data 131 and the compressed audio data 133 in accordance withthe predetermined algorithm. The microprocessor monitors the capacity ofthe compressed picture data 131 and the compressed audio data 133respectively stored in the video data buffer 17 and the audio databuffer 18, and maintains the condition for preventing these data fromoverflowing or underflowing. Under such a condition, the microprocessorcontrols the reading out of the video data 103 and the audio data 104from the video data buffer 17 and the audio data buffer 18, respectivelyin units of the sector to be interleaved. In the AV interleaving circuit51, the GOP data 206 is generated through the interleaving process, andthe obtained GOP data 260 is transferred to the pointer interleavingcircuit 52 as a GOP data signal 139. The AV interleaving circuit 51 alsotransfers the location data of the independent picture data 261 and theaudio data 263 included in the generated GOP data 260 to themicrocontroller 25 as the interleave data 135.

The pointer interleaving circuit 52 is a selector circuit fortransferring the control data 102 or the GOP data 260 read out from thecontrol data buffer 13 to the data recording circuit 35 in accordancewith the data switching signal 137 output from the microcontroller 25.The microcontroller 25 outputs the data switching signal 137 forselecting the GOP data 260 in the recording operation of the chapterdata and for selecting the control data 102 in recording operation ofthe global pointer data 250, the picture pointer data 230, and the audiopointer data 430, thereby switching the contents of the recording data134.

Next, an ordinary recording operation for an AV file 410 (describedbelow referring to FIG. 12) by the data recording/reproducing apparatus400 having the aforementioned configuration will be described withreference to a flowchart shown in FIG. 11.

(S1101) An operator starts the recording operation by determining therecording start position in the AV file 410 and selecting the ordinaryrecording operation mode through the front panel 24. Such a recordingcondition is set in the microcontroller 25 as the operation mode controlsignal 110.

(S1102) The microcontroller 25 calculates the address of a startingsector for storing the first chapter data 440 by adding the number ofsectors for recording the global pointer data 450, the picture pointerdata 230 and the audio pointer data 430 at the top portion of the AVfile 410 to the address of the determined recording start position.Then, the microcontroller 25 sets the calculated address in the diskdrive unit 10 as the drive control signal 113, and instructs theexecution of the seek operation. The microcontroller 25 also sets theaddress in the data recording circuit 35 as a recording operationcontrol signal 138.

(S1103) The microcontroller 25 actuates the video encoder circuit 32 andthe audio encoder circuit 33. The compressed picture data 131 and thecompressed audio data 133 respectively generated by the video encodercircuit 32 and the audio encoder circuit 33 are stored in the video databuffer 17 and the audio data buffer 18, respectively, in units of asector. The interleaving circuit 34 interleaves the compressed picturedata 131 and the compressed audio data 133 in accordance with thepredetermined algorithm, while reading them out in units of a sector,and the thus generated GOP data is transferred as the recording data134. The interleaving circuit 34 simultaneously transfers to themicrocontroller 25 the location of the audio data 470 and theindependent picture data 261 in the GOP data as the interleave data 135.The data recording circuit 35 discriminates an address signal previouslyrecorded at the header field of each sector from the reproducing signal100 and demodulates the discriminated signal, and detects whether or notit is matched with the address set as the recording operation controlsignal 138 in step S1102. When the addresses are matched, the datarecording circuit 35 writes the recording signal 136 generated throughthe ECC process and the modulation process of the recording data 134 inthe data field of that particular sector. Such a data recordingoperation is continuously performed on all the sectors contained in theGOP. Further, while recording the data on the recording medium, themicrocontroller 25 generates respective prepointers of the audio pointerdata 430 and the picture pointer data 230 based on the interleave data135 transferred from the interleaving circuit 34, and the generatedprepointers are stored in the audio pointer write buffer 29 and thepicture pointer write buffer 27. At this point, the microcontroller 25simultaneously updates the number of the registered prepointers in theaudio pointer write buffer 29 and the picture pointer write buffer 27.

(S1104) The data recording operation on each GOP described in step S1103is repeated a predetermined number of times. When the recordingoperation of the GOP data is repeated the predetermined number of times,the recording operation of the chapter data 240 is completed.

(S1105) When the recording operation of the chapter data 240 iscompleted, the picture pointer write buffer 27 and the audio pointerwrite buffer 29 respectively store the picture pointer data 230 and theaudio pointer data 430 including the prepointers alone. Themicrocontroller 25 outputs the data switching signal 137 fortransferring these pointer data to the data recording circuit 35. Theinterleaving circuit 34 reads out these pointer data from the controldata buffer 13 to be transferred to the data recording circuit 35. Thedata recording circuit 35 writes the picture pointer data and the audiopointer data in areas immediately after the area where the chapter datais written. The interleaving circuit 34 transfers the location data ofthese pointer data to the microcontroller 25 as the interleave data 135.The microcontroller 25 generates global pointers 451 for indicating thelocations of the picture pointer data 230 and the audio pointer data 430from the interleave data 135, and stores them in the global pointerbuffer 15. At this point, the microcontroller 25 simultaneously updatesthe number of the registered global pointers in the global pointerbuffer 15.

(S1106) The microcontroller 25 detects whether or not the stop keyprovided on the front panel 24 is pushed (i.e., a stop command isinput). If not, the microcontroller 25 outputs to the interleavingcircuit 34 the data switching signal 137 for transferring the compressedpicture data 131 and the compressed audio data 133 to the data recordingcircuit 35.

(S1107) When the stop key is detected to have been pushed, it means thatall the location data of the picture pointer data 230 and the audiopointer data 430 are already stored in the global pointer buffer 15.When the microcontroller 25 outputs the data switching signal 137 forinstructing the transfer of the global pointer data 450, theinterleaving circuit 34 transfers the global pointer data 450 receivedfrom the control data buffer 13 to the data recording circuit 35. Thedata recording circuit 35 writes the global pointer data 450 in an areasubsequently to the last recorded audio pointer data 430.

(S1108) Through the recording operation described so far, i pieces ofthe picture pointer data 230 and i pieces of the audio pointer data 430respectively located from the 2nd to the (i+1)th respective positions inthe AV file are recorded on the recording medium. Each piece of thepicture pointer data 230 and the audio pointer data 430 has the datastructure including a plurality of the prepointers alone. Next, themicrocontroller 25 searches and retrieves the global pointer data 450 soas to read out the ith picture pointer data 230(i) and the ith audiopointer data 430(i) in the picture pointer write buffer 27 and the audiopointer write buffer 29, respectively. Then, the microcontroller 25reads out the (i+1)th picture pointer data 230(i+1) and the (i+1)thaudio pointer data 430(i+1) in the picture pointer read buffer 16 andthe audio pointer read buffer 28, respectively. Also, themicrocontroller 25 transfers the prepointers stored in the picturepointer read buffer 16 and the audio pointer read buffer 28 to thepicture pointer write buffer 27 and the audio pointer read buffer 29,respectively, as the respective postpointers. Through this procedure,the picture pointer data 230 and the audio pointer data 430 includingboth the prepointers and the postpointers are generated. Then, themicrocontroller 25 controls updating the generated ith picture pointerdata 230(i) and the ith audio pointer data 430(i) on the recordingmedium.

(S1109) The microcontroller 25 executes updating picture pointer data230 and audio pointer data 430 from the ith to the 2nd pieces of them.In the end, the microcontroller 25 records the 1st picture pointer data230 and the 1st audio pointer data 430 including the postpointers alone,and thus, the recording operation of the pointer data is completed.

(S1110) Next, the microcontroller 25 records at the top of the AV file,as the first global pointer data 450, a data having the same content asthe second global pointer data 450 recorded at the end of the AV file410 in the step S1107.

(S1111) Finally, the microcontroller 25 generates a file entry having amanagement data for the recorded AV file in the file control buffer.Then, the file control data 220 recorded in the file management area onthe recording medium is updated.

Through the processing procedures as described above, one AV file 410 isrecorded on the data recording medium. In the above description, afterthe pointer data including the prepointers alone is once recorded in thestep S1105, the pointer data 230 and 430 are updated to include both thepostpointers and the prepointers in the step S1108. In the recordingoperation for the AV file 410 through such processing procedures, thepointer data 230 and 430 are recorded simultaneously with the recordingof the chapter data 440. Therefore, if any trouble occurs in the powersupply during the recording of the AV file 410, all the pointer data 230and 430 related to the chapter data 440 having recorded by the time ofthe occurrence of the trouble are already recorded on the recordingmedium as the prepointers 232 and 432. Accordingly, if an AV file 410having incomplete pointer data is recorded on the medium, the recoveryprocess can be performed easily while keeping the stored chapter data440 as follows: The microcontroller 25 executes the data reproducingoperation on all the sectors included in the recording area of this AVfile 410, detects the address of a sector 201 where the data type code207 indicating the control data is recorded in its sub-code field 204,and stores the address in the global pointer buffer 15 as the globalpointer 251. Then, the microcontroller 25 further executes theprocedures subsequent to the step S1107, thereby recording the picturepointer data 230 and the audio pointer data 430 including both thepostpointers and the prepointers on the recording medium.

FIG. 12 shows the data structure of the AV file 410 recorded on therecording medium in through the aforementioned operation. The datastructure shown in FIG. 12 is different from that shown in FIG. 2 inthat the audio pointer data 430 are always recorded subsequently to thepicture pointer data 230. The order of the audio pointer data 430 andthe picture pointer data 230 can be exchanged. The audio pointer data430, which is read out during the postrecording operation, is locatedalternately with the chapter data 440. In FIG. 12, each global pointer451 is shown as to directly indicate the location of the audio pointerdata 430 for simplification of the description of the postrecordingoperation. Each global pointer 451, however, simultaneously indicatesthe location of the picture pointer data 230 similarly to the structureof FIG. 2. Specifically, each global pointer 451 is formed so as to havea pair of absolute addresses respectively indicating the locations ofthe picture pointer data 230 and the audio pointer data 430. Thelocation of the audio pointer data 430 can be set as an offsetrepresentation from the picture pointer data 230. It is noted that thedata structure shown in FIG. 12 is applied to a rewritable recordingmedium alone because it is used for attaining the postrecordingfunction, but that the data structure shown in FIG. 2 is applicable toboth the recording medium for the read-only and for the rewritablerecording medium requiring no postrecording function.

When the location of the audio data 470 is managed by using theaforementioned hierarchical data structure, the capacity of the globalpointer data 450 and the audio pointer data 430 are calculated asfollows: It is assumed that the reproducing time for each chapter datais 1 minute in a movie title of 135 minutes. In this case, the globalpointer data 450 includes 135 global pointers 451. When a stereo audiodata signal is compressed into a data rate of 224 Kbps, the compressedaudio data per 1 minute is 1,680 KB, and is recorded by using 840sectors. Accordingly, when the audio data 470 is located by using theinterleaved format shown in FIG. 3A, 840 prepointers 432 and 840postpointers 431 are registered in each audio pointer data 430. When itis assumed that these pointers have the addresses of the respectivesectors represented by four byte length, each of the prepointer 432 andthe postpointer 431 has a capacity of 3,360 bytes, and is recorded byusing two sectors.

When the audio data 470 is located by using the non-interleaved formatas shown in FIG. 3B, the chapter data 440 includes 150 audio data 470,which is the same number as that of the GOP. Therefore, 150 prepointers432 and 150 postpointers 431 are registered in each audio pointer data430. When it is assumed that each pointer includes a combination of thestart address (an absolute value representation of four byte length) andthe last address (an offset representation of two byte length) of theaudio data 470, the audio pointer data 430 has a capacity of 1,800bytes, and is recorded by using one sector. The global pointer 451indicating the location of the audio pointer data 430 has the sectoraddress alone (four byte length representation), and hence, the capacityof the global pointer data 450 is 540 bytes. Accordingly, when eachglobal pointer 451 is formed so as to have a pair of absolute addressesrespectively indicating the locations of the picture pointer data 230and the audio pointer data 430 as described above, the global pointerdata 451 has a capacity of 1,080 bytes, and is recorded in one sector.

In order to retrieve the location of the audio data 430 in thepostrecording operation, either of the prepointers 432 or thepostpointers 431 of the audio pointer data 430 and the global pointerdata 450 are required to be stored in the apparatus. Therefore, thememory capacity for storing these pointers read out from the recordingmedium is 6 KB in total (corresponding to three sectors) when theinterleaved format is used and 4 KB (corresponding to two sectors) whenthe non-interleaved format is used. Thus, the buffer capacity, which isrequired to be 450 KB or 80 KB in the conventional apparatus asdescribed above, can be greatly decreased.

The postrecording operation for the AV file 410 by the datarecording/reproducing apparatus 400 of the present invention will now bedescribed referring to a flowchart shown in FIG. 13. It is assumed, forsimplification, that the AV file 410 includes three chapter data 440,and that each chapter data 440 includes four sectors 201 for storing theaudio data 470. It is also assumed that the contents of the four audiopointer data 430 having the location data of the sectors 201 storing theaudio data 470 are set as listed in Table 2.

                  TABLE 2                                                         ______________________________________                                                    Prepointers Postpointers                                          ______________________________________                                        Audio Pointer ( Unused )    Address (A 1)                                     Data 1        ( Unused )    Address (A 2)                                                   ( Unused )    Address (A 3)                                                   ( Unused )    Address (A 4)                                     Audio Pointer Address (A 1) Address (A 5)                                     Data 2        Address (A 2) Address (A 6)                                                   Address (A 3) Address (A 7)                                                   Address (A 4) Address (A 8)                                     Audio Pointer Address (A 5) Address (A 9)                                     Data 3        Address (A 6) Address (A 1 0)                                                 Address (A 7) Address (A 1 1)                                                 Address (A 8) Address (A 1 2)                                   Audio Pointer Address (A 9) ( Unused )                                        Data 4        Address (A 1 0)                                                                             ( Unused )                                                      Address (A 1 1)                                                                             ( Unused )                                                      Address (A 1 2)                                                                             ( Unused )                                        ______________________________________                                    

Also, in the following description, it is assumed that the file controldata 220 recorded on the recording medium has already been read out andstored in the file control data buffer 14 when the medium was loaded orreset.

(S1301) The operator selects an AV file 410 for executing thepostrecording operation and determines the postrecording operation modethrough the front panel 24, thereby actuating the datarecording/reproducing apparatus 400. Such a recording condition is setin the microcontroller 25 as the operation mode control signal 110.

(S1302) The microcontroller 25 searches and retrieves the location ofthe specified AV file 410 from the file control data buffer 14 so as toread out the file control data. Then, the microcontroller 25 executesthe reproducing operation of the first global pointer data 450 recordedat the top portion of the AV file 410. When the data reproducingoperation is normally completed, the global pointer data 450 is storedin the global pointer buffer 15.

(S1303) When the detection of an uncorrectable error is informed by thedata reproducing circuit 11 in step S1302, the microcontroller 25executes, as the recovery process, the reproducing operation of thesecond global pointer data 450 recorded at the end portion of the AVfile 410 in accordance with the processing procedure as used in the stepS1302.

(S1304) The microcontroller 25 searches and retrieves the location of anaudio pointer data 430(1) from the global pointer data 450 in order toexecute the postrecording operation from the top of the AV file, andfurther executes the reproducing operation of the audio pointer data430(1). When the data reproducing operation is normally completed, theaudio pointer data 430(1) is stored in the audio pointer read buffer 28.

(S1305) The microcontroller 25 searches and retrieves the location ofthe audio data from the postpointers 431 of the reproduced audio pointerdata 430(1) in the order of address A1, address A2, etc. (See Table 2).

(S1306) When the detection of an uncorrectable error is informed by thedata reproducing circuit 11 in step S1304, the microcontroller 25executes, as the recovery process, the reproducing operation of an audiopointer data 430(2) which is the subsequent audio pointer data, inaccordance with the same processing procedure as used in the step S1304.

(S1307) The microcontroller 25 searches and retrieves the location ofthe audio data from the prepointers 432 of the audio pointer data430(2).

(S1308) When the location of the audio data 470 is detected, themicrocontroller 25 sets the retrieved address in the disk drive unit 10as the drive control signal 113, and instructs the seek operation.Further, the microcontroller 25 also sets the address in the datarecording circuit 35 as the recording operation control signal 138.Furthermore, the microcontroller 25 actuates the audio encoder circuit33. The compressed audio data 133 generated by the audio encoder circuit33 is stored in the audio data buffer 18 in units of a sector. When theinterleaving circuit 34 outputs the compressed audio data 133 as therecording data 134, the data recording circuit 35 detects a sectorhaving the set address, and writes the recording signal 136 which isobtained for the recording data 134 through the ECC process and themodulation process.

(S1309) The microcontroller 25 detects whether or not the stop key onthe front panel 24 is pushed (i.e., a stop command is input), andterminates the postrecording operation if the key is pushed. Further,when the microcontroller 25 retrieves all the audio pointers to besearched, the microcontroller 25 detects that the AV file 410 ispostrecorded to the end and terminates this operation.

(S1310) The microcontroller 25 searches and retrieves the prepointer 432or the postpointer 431 corresponding to the subsequent audio data 430from the audio pointer read buffer 28. When the subsequent audio pointeris detected, the microcontroller 25 executes the recording operation ofthe subsequent audio data 430 by returning to step S1308. When, forexample, an address A4 is detected as the postpointer 431 in the stepS1305, an address A5, that is, the subsequent postpointer, is notincluded in the audio pointer data 430(1) which has been stored in theaudio pointer read buffer. In this case, the microcontroller 25 executesthe reproducing operation of the subsequent audio pointer data 430(2) byreturning to step S1304 (See Table 2).

(S1311) When the reproducing operations of the global pointer data 450or the audio pointer data 430 are not normally completed in steps S1303or the step S1306, respectively, the microcontroller 25 suspends thepostrecording operation and displays a data reproducing error message.

As described above, in the data recording/reproducing apparatus 400 ofthe present invention, the global pointer data 450 and the audio pointerdata 430 are previously read out in the memory circuits, the location ofthe audio data 470 is determined while retrieving the read data, andrecording is performed while compressing externally input audio data. Itis noted that when the error recovery process described in the stepsS1303 and S1306 is not executed, the data recording/reproducingapparatus 400 can execute the postrecording operation by using arecording medium where the global pointer data and the audio pointerdata are not multiply recorded.

In the audio compression method defined in the MPEG standard and thelike, audio data is constant-bitrate-compressed. Therefore, when theaudio data 470 is recorded in the step S1308, there is no fear oferroneously rewriting the video data (picture data 270) locatedimmediately after or before the audio data 470. In step S1308, the audioencoder circuit 33 is designed to compress the externally input audiorecording signal. However, when the audio data 470 recorded on therecording medium is uncompressed, the microcontroller 25 may determinean operation mode for uncompressed data, and the audio encoder circuit33 can generate uncompressed audio data and record it on the recordingmedium. Therefore, the postrecording operation described above isapplicable to both the compressed audio data and the uncompressed audiodata.

According to the data recording medium of the present invention, thelocations of the independent picture data which is arranged on the datarecording medium at unequal intervals are managed by using thehierarchical management data including the picture pointer data formanaging the location data of the independent picture data and theglobal pointer data for managing the location data of the picturepointer data. By using such a data recording medium, the datareproducing apparatus never requires a bulk memory to store all thelocation data of the independent picture data in the trickplay mode. Itis possible to perform a rapid trickplay mode operation using memorycircuits having only a small capacity by retrieving the locations of theindependent picture data in a stepwise manner.

Further, according to the data reproducing apparatus and the datareproducing method of the present invention, the locations of theindependent picture data located at unequal intervals are retrieved andreproduced by the hierarchical management data including the globalpointer data and the picture pointer data. Therefore, in the datareproducing apparatus, since there is no need for a bulk memory forstoring all the location data of the independent picture data in thetrickplay mode operation, it is possible to perform a rapid trickplaymode operation by retrieving the locations of the independent picturedata in a stepwise manner by using memory circuits with small capacity.

Moreover, the global pointer data is doubly recorded at the top portionand the end portion of each AV file, and the picture pointer data isalso doubly recorded corded by using the postpointers and theprepointers. Accordingly, the efficiency of the trickplay mode can beincreased, and the error recovery function can be largely enhancedwithout greatly increasing the data amount.

Further, according to the present invention, the locations of the audiodata located on the data recording medium at unequal intervals aremanaged by using the hierarchical management data including the audiopointer data for managing the location data of the audio data and theglobal pointer data for managing the location data of the audio pointerdata.

According to the data recording/reproducing apparatus and the datarecording/reproducing method having the postrecording function of thepresent invention, the locations of the audio data located at unequalintervals are retrieved and reproduced by using the hierarchicalmanagement data including the global pointer data and the audio pointerdata. As a result, there is no need for the bulk memory of the locationdata of the entire audio data in the postrecording operation. Therefore,the capacity of the used buffer can be largely decreased, resulting inrealizing an inexpensive compact data recording/reproducing apparatus.

Furthermore, the global pointer data is doubly recorded at the top andend portions of each AV file, and the audio pointer data is also doublyrecorded by using the postpointers and the prepointers. As a result, theefficiency of the postrecording operation can be increased, and theerror recovery function can be largely enhanced without largelyincreasing the data amount.

Various other modifications will be apparent to and can be readily madeby those skilled in the art without departing from the scope and spiritof this invention. Accordingly, it is not intended that the scope of theclaims appended hereto be limited to the description as set forthherein, but rather that the claims be broadly construed.

What is claimed is:
 1. A data recording medium having a plurality ofunits with a fixed length for recording AV files each including thevideo data that is compressed in units of a picture on thevariable-bitrate condition,wherein each of the AV files recorded on thedata recording medium includes a plurality of chapter data including aplurality of GOP data, a plurality of first pointer data each having aplurality of first pointers, and at least one second pointer data havinga plurality of second pointers; each of the GOP data includes oneindependent picture data that is intra-picture compressed and aplurality of dependent picture data that are inter-picture compressed;each of the first pointers is provided in a one-to-one correspondence toeach of the independent picture data, and stores a location data of thecorresponding independent picture data; each of the second pointers isprovided in a one-to-one correspondence to each of the first pointerdata and stores a location data of the corresponding first pointer data;and a hierarchical location data for retrieving the independent picturedata is formed by the first pointers and the second pointers.
 2. A datarecording medium according to claim 1, wherein each of the chapter datais arranged adjacent to one of the first pointer data which includes thefirst pointers corresponding to the independent picture data included inthat particular chapter data.
 3. A data recording medium according toclaim 1, wherein the chapter data and the first pointer data arealternately located, and each of the first pointer data includes thefirst pointers corresponding to the independent picture data included inthe chapter data adjacent to that particular first pointer data.
 4. Adata recording medium according to claim 1, wherein the second pointerdata is located at the top and/or end portions of each of the AV files,andthe second pointer data includes all of the second pointerscorresponding to the first pointer data included in the corresponding AVfile, thereby storing the location data on all of the first pointer dataincluded in the corresponding AV file.
 5. A data recording mediumaccording to claim 1, wherein each of the GOP data further includesaudio data.
 6. A data recording medium according to claim 5,wherein theaudio data is interleaved with the independent picture data and thedependent picture data of the basis of each unit with the fixed length,and a data type code for discriminating the independent picture data isrecorded in each unit with the fixed length.
 7. A data recording mediumaccording to claim 1,wherein a padding data is added to the independentpicture data, whereby the independent picture data to which the paddingdata is added completes each unit with the fixed length, and a validdata length for discriminating the padding data is recorded in each unitwith the fixed length.
 8. A data recording medium having a plurality ofunits with a fixed length for recording AV files each including thevideo data that is compressed in units of a picture on thevariable-bitrate condition,wherein each of the AV files recorded on thedata recording medium includes a plurality of chapter data including aplurality of GOP data, a plurality of first pointer data each having aplurality of first pointers, and at least one second pointer data havinga plurality of second pointers; each of the GOP data includes at leastone picture data and at least one audio data; each of the first pointersis provided in a one-to-one correspondence to each of the audio data andstores location data of the corresponding audio data; each of the secondpointers is provided in a one-to-one correspondence to each of the firstpointer data and stores location data of the corresponding first pointerdata; and a hierarchical location data for retrieving the audio data isformed by the first pointers and the second pointers.
 9. A datarecording medium according to claim 8, wherein each of the chapter datais arranged adjacent to one of the first pointer data including thefirst pointers corresponding to the audio data included in thatparticular chapter data.
 10. A data recording medium according to claim8, wherein the chapter data and the first pointer data are alternatelylocated, and each of the first pointer data includes the first pointerscorresponding to the audio data included in the chapter data adjacent tothat particular first pointer data.
 11. A data recording mediumaccording to claim 8, wherein the second pointer data is located at thetop portion and/or end portion of each of the AV files, andthe secondpointer data includes all of the second pointers corresponding to thefirst pointer data included in the corresponding AV file, therebystoring the location data on all of the first pointer data included inthe corresponding AV file.